Total Synthesis and Evaluation of c26-Hydroxyepothilone D Derivatives for Photoaffinity Labeling of β-Tubulin

Three photaffinity labeled derivatives of epothilone D were prepared by total synthesis, using efficient novel asymmetric synthesis methods for the preparation of two important synthetic building blocks. The key step for the asymmetric synthesis of (S,E)-3-(tert-butyldimethylsilyloxy)-4-methyl-5-(2-methylthiazol-4-yl)pent-4-enal involved a ketone reduction with (R)-Me-CBS-oxazaborolidine. For the synthesis of (5S)-5,7-di-[(tert-butyldimethylsilyl)oxy]-4,4-dimethylheptan-3-one an asymmetric Noyori reduction of a β-ketoester was employed. The C26 hydroxyepothilone D derivative was constructed following a well-established total synthesis strategy and the photoaffinity labels were attached to the C26 hydroxyl group. The photoaffinity analogues were tested in a tubulin assembly assay and for cytotoxicity against MCF-7 and HCT-116 cancer cell lines. The 3- and 4-azidobenzoic acid analogues were found to be as active as epothilone B in a tubulin assembly assay, but demonstrated significantly reduced cellular cytotoxicity compared to epothilone B. The benzophenone analogue was inactive in both assays. Docking and scoring studies were conducted that suggested that the azide analogues can bind to the epothilone binding site, but that the benzophenone analogue undergoes a sterically driven ligand rearrangement that interrupts all hydrogen bonding and therefore protein binding. Photoaffinity labeling studies with the 3-azidobenzoic acid derivative did not identify any covalently labeled peptide fragments, suggesting that the phenylazido side chain was predominantly solvent-exposed in the bound conformation

Total synthesis and evaluation of 22-(3-azidobenzoyloxy)methyl epothilone C for photoaffinity labeling of β-tubulin

The total synthesis of 22-(3-azidobenzoyloxy)methyl epothilone C is described as a potential photoaffinity probe to elucidate the β-tubulin binding site. A sequential Suzuki-aldol-Yamaguchi macrolactonization strategy was utilized employing a novel derivatized C1–C6 fragment. The C22-functionalized analog exhibited good activity in microtubule assembly assays, but cytotoxicity was significantly reduced. Molecular modeling simulations indicated that excessive steric bulk in the C22 position is accommodated by the large hydrophobic pocket of the binding site. Photoaffinity labeling studies were inconclusive suggesting non-specific labeling

A Chromatic Treatment of Linear Polarization in the Solar Corona at the 2023 Total Solar Eclipse

The broadband solar K-corona is linearly polarized due to Thomson scattering. Various strategies have been used to represent coronal polarization. Here, we present a new way to visualize the polarized corona, using observations from the 2023 April 20 total solar eclipse in Australia in support of the Citizen CATE 2024 project. We convert observations in the common four-polarizer orthogonal basis (0{\deg}, 45{\deg}, 90{\deg}, & 135{\deg}) to -60{\deg}, 0{\deg}, and +60{\deg} (MZP) polarization, which is homologous to R, G, B color channels. The unique image generated provides some sense of how humans might visualize polarization if we could perceive it in the same way we perceive color.Comment: 4 pages, 1 figure; accepted for publication in Research Notes of the American Astronomical Society (RNAAS

Effects of Paramagnetic Ferrocenium Cations on the Magnetic Properties of the Anionic Single-Molecule Magnet [Mn12O12(O2CC6F5)16(H2O)4]-

The preparation and physical characterization are reported for several single-molecule magnet salts to investigate the effects of paramagnetic cations on the magnetization relaxation behavior of [Mn12]- anionic single-molecule magnets.Comment: 30 pages, 5 tables, 15 figure

Global 30–240 keV proton precipitation in the 17–18 April 2002 geomagnetic storms: 1. Patterns

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95215/1/jgra18503.pd

Recurrent heterozygous PAX6 missense variants cause severe bilateral microphthalmia via predictable effects on DNA-protein interaction

Purpose: Most classical aniridia is caused by PAX6 haploinsufficiency. PAX6 missense variants can be hypomorphic or mimic haploinsufficiency. We hypothesized that missense variants also cause previously undescribed disease by altering the affinity and/or specificity of PAX6 genomic interactions. Methods: We screened PAX6 in 372 individuals with bilateral microphthalmia, anophthalmia, or coloboma (MAC) from the Medical Research Council Human Genetics Unit eye malformation cohort (HGUeye) and reviewed data from the Deciphering Developmental Disorders study. We performed cluster analysis on PAX6-associated ocular phenotypes by variant type and molecular modeling of the structural impact of 86 different PAX6 causative missense variants. Results: Eight different PAX6 missense variants were identified in 17 individuals (15 families) with MAC, accounting for 4% (15/372) of our cohort. Seven altered the paired domain (p.[Arg26Gln]x1, p.[Gly36Val]x1, p.[Arg38Trp]x2, p.[Arg38Gln]x1, p.[Gly51Arg]x2, p.[Ser54Arg]x2, p.[Asn124Lys]x5) and one the homeodomain (p.[Asn260Tyr]x1). p.Ser54Arg and p.Asn124Lys were exclusively associated with severe bilateral microphthalmia. MAC-associated variants were predicted to alter but not ablate DNA interaction, consistent with the electrophoretic mobility shifts observed using mutant paired domains with well-characterized PAX6-binding sites. We found no strong evidence for novel PAX6-associated extraocular disease. Conclusion: Altering the affinity and specificity of PAX6-binding genome-wide provides a plausible mechanism for the worse-than-null effects of MAC-associated missense variants

Mutation Detection in Patients with Retinal Dystrophies Using Targeted Next Generation Sequencing

Retinal dystrophies (RD) constitute a group of blinding diseases that are characterized by clinical variability and pronounced genetic heterogeneity. The different nonsyndromic and syndromic forms of RD can be attributed to mutations in more than 200 genes. Consequently, next generation sequencing (NGS) technologies are among the most promising approaches to identify mutations in RD. We screened a large cohort of patients comprising 89 independent cases and families with various subforms of RD applying different NGS platforms. While mutation screening in 50 cases was performed using a RD gene capture panel, 47 cases were analyzed using whole exome sequencing. One family was analyzed using whole genome sequencing. A detection rate of 61% was achieved including mutations in 34 known and two novel RD genes. A total of 69 distinct mutations were identified, including 39 novel mutations. Notably, genetic findings in several families were not consistent with the initial clinical diagnosis. Clinical reassessment resulted in refinement of the clinical diagnosis in some of these families and confirmed the broad clinical spectrum associated with mutations in RD genes

SCORE2-Diabetes: 10-year cardiovascular risk estimation in type 2 diabetes in Europe

Aims: To develop and validate a recalibrated prediction model (SCORE2-Diabetes) to estimate the 10-year risk of cardiovascular disease (CVD) in individuals with type 2 diabetes in Europe. Methods and results: SCORE2-Diabetes was developed by extending SCORE2 algorithms using individual-participant data from four large-scale datasets comprising 229 460 participants (43 706 CVD events) with type 2 diabetes and without previous CVD. Sex-specific competing risk-adjusted models were used including conventional risk factors (i.e. age, smoking, systolic blood pressure, total, and HDL-cholesterol), as well as diabetes-related variables (i.e. age at diabetes diagnosis, glycated haemoglobin [HbA1c] and creatinine-based estimated glomerular filtration rate [eGFR]). Models were recalibrated to CVD incidence in four European risk regions. External validation included 217 036 further individuals (38 602 CVD events), and showed good discrimination, and improvement over SCORE2 (C-index change from 0.009 to 0.031). Regional calibration was satisfactory. SCORE2-Diabetes risk predictions varied several-fold, depending on individuals' levels of diabetes-related factors. For example, in the moderate-risk region, the estimated 10-year CVD risk was 11% for a 60-year-old man, non-smoker, with type 2 diabetes, average conventional risk factors, HbA1c of 50 mmol/mol, eGFR of 90 mL/min/1.73 m2, and age at diabetes diagnosis of 60 years. By contrast, the estimated risk was 17% in a similar man, with HbA1c of 70 mmol/mol, eGFR of 60 mL/min/1.73 m2, and age at diabetes diagnosis of 50 years. For a woman with the same characteristics, the risk was 8% and 13%, respectively. Conclusion: SCORE2-Diabetes, a new algorithm developed, calibrated, and validated to predict 10-year risk of CVD in individuals with type 2 diabetes, enhances identification of individuals at higher risk of developing CVD across Europe

Neurexins and Neuroligins: Recent Insights from Invertebrates

During brain development, each neuron must find and synapse with the correct pre- and postsynaptic partners. The complexity of these connections and the relatively large distances some neurons must send their axons to find the correct partners makes studying brain development one of the most challenging, and yet fascinating disciplines in biology. Furthermore, once the initial connections have been made, the neurons constantly remodel their dendritic and axonal arbours in response to changing demands. Neurexin and neuroligin are two cell adhesion molecules identified as important regulators of this process. The importance of these genes in the development and modulation of synaptic connectivity is emphasised by the observation that mutations in these genes in humans have been associated with cognitive disorders such as Autism spectrum disorders, Tourette syndrome and Schizophrenia. The present review will discuss recent advances in our understanding of the role of these genes in synaptic development and modulation, and in particular, we will focus on recent work in invertebrate models, and how these results relate to studies in mammals